"It was the Friday before Memorial Day weekend, 2003, and the hearing room in the Hart Senate Office Building, in Washington, was half empty as the group of mostly retired military brass arranged themselves at the witness table before the 9/11 commission. The story the norad officers had come to tell before the commission was a relatively humbling one, a point underscored by the questions commission chairman Thomas Kean introduced during his opening remarks: How did the hijackers defeat the system, and why couldn't we stop them? These were important questions. Nearly two years after the attack, the Internet was rife with questions and conspiracy theories about 9/11—in particular, where were the fighters? Could they have physically gotten to any of the hijacked planes? And did they shoot down the final flight, United 93, which ended up in a Pennsylvania field?"